EP0567419A2 - A shifter-based rim phase shifting structure and process to fabricate the same - Google Patents

A shifter-based rim phase shifting structure and process to fabricate the same Download PDF

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Publication number
EP0567419A2
EP0567419A2 EP93480023A EP93480023A EP0567419A2 EP 0567419 A2 EP0567419 A2 EP 0567419A2 EP 93480023 A EP93480023 A EP 93480023A EP 93480023 A EP93480023 A EP 93480023A EP 0567419 A2 EP0567419 A2 EP 0567419A2
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EP
European Patent Office
Prior art keywords
layer
phase
blocker
shifting
absorber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP93480023A
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German (de)
English (en)
French (fr)
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EP0567419A3 (enrdf_load_stackoverflow
Inventor
Jeng Lin Burn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Business Machines Corp
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International Business Machines Corp
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Filing date
Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Publication of EP0567419A2 publication Critical patent/EP0567419A2/en
Publication of EP0567419A3 publication Critical patent/EP0567419A3/xx
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/26—Phase shift masks [PSM]; PSM blanks; Preparation thereof
    • G03F1/29—Rim PSM or outrigger PSM; Preparation thereof

Definitions

  • This invention relates to masks for lithography and more particularly to photolithographic phase-shift masks.
  • the phase-shifting technique can improve the resolution of coherent or partially coherent optical imaging systems. It has been shown that the normalized resolution k 1 can be reduced from 0.7 ⁇ m to 0.35 ⁇ m to improve lithography by two generations.
  • phase-shifting techniques with masks in optical microlithography systems has been shown to improve projected images. These phase-shifting techniques have been practiced in various configurations.
  • Nitayama et al "New Phase Shifting Mask with Self-Aligned Phase Shifters for Quarter Micron Photolithography", IEDM Technical Digest, pp. 57-60 (1989) shows a mask pattern consisting of a phase-shifting layer and a slightly smaller opaque layer which blocks tight at the center of the mask pattern as shown in FIG. 1 herein, described below.
  • FIGS. 1A and 1 B The configuration of a prior art type of rim phase-shift-ing mask of Nitayama et al, above, is shown in FIGS. 1A and 1 B, where a given mask pattern consists of a substrate 10 carrying a phase-shifting layer 12 and a slightly smaller opaque layer 11 which blocks light at the center of the mask pattern.
  • FIG. 1A is a top view of the mask and
  • FIG. 1 Bis a schematic sectional view taken along line 1 B-1 B in FIG. 1A.
  • This arrangement lends itself to strong enhancement of edge contrast due to the phase-shifting, yet prevents a large negative amplitude at the center of patterns to form ghost lines.
  • phase-shifting effect is generally applicable to any given pattern shapes. This is more preferable than alternating-element phase-shifting of Levenson et al, above, or subresolution phase-shifting of Terasawa et al, above, which is applicable to closely packed openings or isolated openings respectively.
  • FIGS. 1A and 1B the configuration of FIGS. 1A and 1B is difficult to practice.
  • Nitayama et al, above teaches delineation of the phase-shifting layer on top followed with a self-aligned overetch of the blocking layer. The undercutting dimension and profile are difficult to control forthe precision required to maintain linewidth control.
  • FIG. 2 is a similar view to FIG. 1 B with a modification of the prior art design of FIGS. 1Aand 1B in accordance with this invention.
  • the phase-shifting layer 12 is the base of the blocking layer 11. This configuration facilitates a better process of fabrication to control the profile and dimensions of the blocking pattern.
  • it also allows inclusion of phase repair layers as described in copending application entitled “A Mask Structure and Process to Repair Missing or Unwanted Phase Shifting Elements", filed at EPO on March 1993 (Fl 9 91 119).
  • contacting the phase shifters to the substrate 10 reduces multiple reflections at the interfaces.
  • FIGS. 3 A-3D show the process of fabrication of the shifter-based rim phase-shifting mask using a two-level exposure.
  • a phase-shifter layer 22 coated in turn with a blocker layer 21, in turn coated with an undeveloped resist layer 26, which has been exposed through a mask, (not shown), which provides three levels of exposure, i.e exposed, partially exposed and unexposed.
  • the resist layer 26 is exposed at full dosage at the transparent non-phase-shifted area of the mask and partially exposed at the rim area.
  • FIG. 3B After normal development, in FIG. 3B only the non-phase-shifted area is cleared. All of the fully exposed resist 24 and a fraction of the partially exposed resist 25 on the sides of the fully exposed resist 24 is removed by development of the resist. Then in an etching step using resist 24 and 25 as the etch mask, areas of the blocker layer 21 and the phase shifter 22 beneath the exposed resist is removed thereby delineating features by etching.
  • the remaining unexposed resist 24 of resist 26 is further developed to clear away the remnants of the partially exposed resist 25 leaving exposed surfaces of the etch blockers 21, which are in turn etched away selectively where they are not protected by the fully exposed resist 24.
  • a selective etch which does not attack the phase shifter layer 22 is used so that portions of phase shifter layer 22 extends beyond the periphery of the blocker layer 21.
  • the remaining resist 24 of layer 26 is stripped until there is no more resist thereby completing the fabrication process.
  • the resulting structure is a set of three types of structures 27, 28 and 29.
  • Structures 27 are wide phase shifters with broader phase-shifting layers 22 with ledges 26 at the rims of blocker 21 on layer 22 uncovered where the blocker material 21 on the central portions of structures 27 have been removed at the rims of structures 27.
  • no ledges 26 exist.
  • no phase shift can be caused by structure 28.
  • the phase shifter areas 22 are narrower and so are the blockers 21, so the narrower ledges 26' about the rims of structures 29 are there to provide phase-shifting by a narrower structures 29.
  • FIGS. 4A-4D show the process of fabrication of a capped resist structure with a Blocker-on-Shifter mask using T-shaped etch masks.
  • a substrate 30 is shown coated with a layer of phase shifter 32 coated in turn with a layer of blocker 31, showing the mask substrate before patterning.
  • FIG. 4B shows etch masks produced.
  • a step of coating with a second-etch mask resist 34 and a first-etch mask resist 36 is provided.
  • the Portable Conformable Masking (PCM) resist system or PMMA-on- terpolymer resist system is used in place of the two levels of exposure of resist as in FIGS. 3A-3D. This process is described in "Introduction to Microlithography", Edited by L.F. Thompson, C.G. Willson and M.J. Bowden, ACS Symposium Series 219, Ch. 6 (1963).
  • the two layers of resist 36 and 34 are exposed to a single patterning exposure (not shown.)
  • the first-etch mask 36 provides a etch mask for an anisotropic etch to leave portions of layers 32 and 31 extending beyond the edge of second-etch mask 34.
  • the T-top technique is not limited to PCM or PMMA-on-terpolymer above. Any well known technique to produce an organic or inorganic T-top structure can be used.
  • FIG. 4C shows the first-etch mask 36 removed so that the anisotropic etch removes exposed portions of the blocker 31, leaving exposed ledges of shifter 32 extending beyond blocker 31 at the rim of blocker 31.
  • FIG. 4D shows the selective etch blockerwith the second-etch mask 34 removed by means of a step of resist stripping. What is left is the blocker 31 on top of phase-shifters 32.
  • the exposed ledges 36 of the rim of phase shifter 32 are identical in size whereas the ledges 26 and 26' in FIG. 3D are different in size.
  • Aside-wall deposition process as shown in FIGS. 5A-5F is an alternative to the above-described processes.
  • the second-etch mask 59 can be CVD oxide or a conformally coated polymer.
  • a uniform anisotropic etch back of the conformally deposited second-etch mask 59 in FIG. 5D leaves only the borders 59' of resist 59.
  • the blockers 51 and shifters 52 are now exposed to be etched resulting in the formation of self-aligned sidewalls 60 of shifters 52 with well controlled thickness.
  • the first etch mask 54 is removed after the process of FIG. 5E is completed.
  • Mask 54 is made of silicon or polysilicon.
  • the blockers 51 are inset from the walls of the shifters 52 in FIG. 5F.
  • a thin inorganic material deposited on the absorber before resist coating can be used to broaden the choice of processes 1 to 3 above.
  • the task of delineating the absorber and a relatively much thicker phase shifterwithout having to realign is now reduced to delineating only two thin layers.
  • the image in these two thin layers is then used to delineate the phase shifter.
  • the two-level exposure process is now used to teach the concept.
  • FIG. 6A shows the mask substrate 60 consisting of a resist layer 61, a thin inorganic layer 62 and an absorber layer 63 deposited on the substrate 60 in reverse order as will be well understood by those skilled in the art.
  • the material of the thin inorganic layer 62 can be aluminum, S 13 N 4 , or many others, as will become clear in the following teachings.
  • the resist layer 61 receives the programmed three levels of exposure as before, with areas 64 partially exposed and areas 65 unexposed.
  • the aluminum/absorber stack 62/63 is delineated using the resist image developed during the first development time as shown in FIG. 6B.
  • the resist 61 is further developed to open the partially exposed areas 64 (leaving unexposed resist65) and the aluminum (inorganic) layer62 is delineated using the new resist image, resulting in a self-aligned smaller aluminum image formed from inorganic layer 62 above the absorber image 63 as shown in FIG. 6C.
  • the absorber layer 63 is used as the etch mask for the phase shifter 66 which, in this case, is simply an etched step formed in the substrate 60, as shown in FIG. 6D and FIG. 6E where the step is made more visible.
  • the absorber layer 63 in areas to be exposed at the rims of layer 63 is now opened with the aluminum layer 62 used as a mask to finish the fabrication process, resulting in the structure shown in FIG. 6E.
  • the absorber etchants or a mixture of the absorber and the aluminum etchant can be used to wet etch the stack of the inorganic layer 62 and absorber layer 63 to result in FIG. 6B. Then, the aluminum etchant is used after developing the partially exposed areas to produce the result of FIG. 6C.
  • the resist 65 can now be stripped and the phase shifter66 can be etched with an anisotropical etch process using the image of absorber 63 as the etch mask.
  • the absorber layer 63 on the rim shifters can be removed with the aluminum inorganic layer 62 as a mask.
  • Si 3 N 4 is another material that can be selectively etched from quartz substrate and can mask the etching of the absorber. It can readily substitute aluminum in this application. In either case, there is no need to remove the inorganic layer after the absorber on the rim is removed.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Preparing Plates And Mask In Photomechanical Process (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
EP93480023A 1992-04-23 1993-03-09 A shifter-based rim phase shifting structure and process to fabricate the same Withdrawn EP0567419A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US87278192A 1992-04-23 1992-04-23
US872781 1992-04-23

Publications (2)

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EP0567419A2 true EP0567419A2 (en) 1993-10-27
EP0567419A3 EP0567419A3 (enrdf_load_stackoverflow) 1994-05-04

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EP93480023A Withdrawn EP0567419A2 (en) 1992-04-23 1993-03-09 A shifter-based rim phase shifting structure and process to fabricate the same

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EP (1) EP0567419A2 (enrdf_load_stackoverflow)
JP (1) JPH0619116A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4415136A1 (de) * 1994-04-25 1995-11-02 Gold Star Electronics Lithographiemaske und Verfahren zu deren Herstellung
WO2004013694A1 (en) * 2002-08-06 2004-02-12 Freescale Semiconductor, Inc. Method of forming a rim phase shifting mask and using the rim phase shifting mask to form a semiconductor device

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5020428B2 (ja) * 1999-08-30 2012-09-05 三星電子株式会社 トップゲート形ポリシリコン薄膜トランジスター製造方法
JP2015102608A (ja) * 2013-11-22 2015-06-04 Hoya株式会社 フォトマスクの製造方法、フォトマスク、パターン転写方法及び表示装置の製造方法
JP2015106001A (ja) * 2013-11-29 2015-06-08 Hoya株式会社 フォトマスクの製造方法、パターン転写方法及び表示装置の製造方法
JP2017076146A (ja) * 2016-12-26 2017-04-20 Hoya株式会社 フォトマスクの製造方法、フォトマスク、パターン転写方法及び表示装置の製造方法
JP2017068281A (ja) * 2016-12-27 2017-04-06 Hoya株式会社 フォトマスクの製造方法、パターン転写方法及び表示装置の製造方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5234780A (en) * 1989-02-13 1993-08-10 Kabushiki Kaisha Toshiba Exposure mask, method of manufacturing the same, and exposure method using the same
US5126006A (en) * 1990-10-30 1992-06-30 International Business Machines Corp. Plural level chip masking
JP2502192B2 (ja) * 1990-11-29 1996-05-29 旭硝子株式会社 位相シフトマスクおよびその製造方法
JP2641362B2 (ja) * 1991-02-27 1997-08-13 エイ・ティ・アンド・ティ・コーポレーション リソグラフィー方法および位相シフトマスクの作製方法

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4415136A1 (de) * 1994-04-25 1995-11-02 Gold Star Electronics Lithographiemaske und Verfahren zu deren Herstellung
WO2004013694A1 (en) * 2002-08-06 2004-02-12 Freescale Semiconductor, Inc. Method of forming a rim phase shifting mask and using the rim phase shifting mask to form a semiconductor device
US6797440B2 (en) 2002-08-06 2004-09-28 Freescale Semiconductor, Inc. Method of forming a rim phase shifting mask and using the rim phase shifting mask to form a semiconductor device

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Publication number Publication date
EP0567419A3 (enrdf_load_stackoverflow) 1994-05-04
JPH0619116A (ja) 1994-01-28

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